1. Field of the Invention
The present invention relates to a lamp apparatus equipped with a base and its manufacturing method.
2. Description of the Related Art
Of bulb type lamp apparatus, a lamp apparatus with a fluorescent lamp mounted to a holder together with a ballast circuit base plate and a base for feeding electric power mounted to the holder is so far known. This base of the fluorescent lamp has a top end of base at one side and a cylindrical threaded portion with the threaded surface at the other side. These base portions are electrically insulated with an insulating portion.
The base is connected with a pair of conductors that are electrically connected to the ballast circuit base plate for feeding electricity. These conductors are connected to the top end of base and the threaded portion, respectively. The conductor is connected to the top end of base using such a technology as soldering or arc welding.
Normally, the top end of base has a flat portion with a through hole formed at nearly its center. The conductor is inserted into the through hole and connected to the base at this flat portion by the soldering or arc welding.
However, there were such problems in the connecting method of a conductor with the top end of base as described above.
Because solder is widely recognized to be a harmful material nowadays, it is desirable to restrain use of it as could as possible.
On the other hand, when connecting a conductor to the top end of base by the arc welding, if they were welded by fusing much amount of them in order to solidly connect, holes might be produced as the top end of base was largely fused. When holes were produced partially on the welded portion, the connected strength of conductor drops largely.
Then, in order to obtain a sufficient welding strength without fusing much amount of the top end of base, a method is now under the examination to pull out the top end of a conductor to the outside of the base and fuse the whole pulled out portion of this conductor. However, according to this method, the conductor material that became solid after welded tends to spread to a partial range. Such partially spread fused material also lowers the connecting strength between the top end of base and the conductor.
Further, when such welded portion is protruding from the top end of base excessively, the welded portion is pushed against the lamp socket terminal for feeding power to a lamp apparatus and as a result, the welded portion may be damaged. If the welded portion is damaged, as a matter of course, the contact with the lamp socket terminal tends to become improper.
Further, when welding a conductor, the top end of base is heated. At this time, the nearly entire top end of base becomes a high temperature. As a result, this heat is transmitted to the insulating portion formed by a glass that is insulating the top end of the base and the threaded portion and may crack them and the top end of base may be peeled off from the insulating portion.
An object of the present invention is to provide a lamp apparatus capable of clearing the above-mentioned problems and a lamp apparatus manufacturing method.
According to the present invention, there is provided a lamp apparatus comprising a lamp body from which first and second conductors are led out; a base mounted to the lamp body, the base including a top end of base with the first conductor electrically connected and a threaded portion with the second conductor electrically connected; and a welded portion that is formed in a convex shape by mixing materials of the top end of base and the first conductor that are welded after they are mutually fused.
According to the present invention, the top end of base and the first conductor are welded through the process wherein they are fused and the welded portion thus formed is in the convex shape and therefore, when the volume of the welded portion is increased by making this convex shaped portion large, the top end of base and the first conductor are solidly connected mechanically.
Further, according to the present invention, there is provided a lamp apparatus comprising a lamp body from which first and second conductors are led out; a base mounted to the lamp body, the base including a top end of base to which a first conductor electrically connected, of which one surface is formed in a flat shape and a dimple formed at near the center of the flat portion; a threaded portion with a second conductor electrically connected; and an insulating member provided between the top end of base and the threaded portion for electrically insulating them; and a welded portion that is formed in a convex shape in the dimple by mixing materials of the top end base and the first conductor that are welded after they are mutually fused.
According to the lamp apparatus of the present invention, as the welded portion is formed in the concave portion, even when the volume of the welded portion is increased, it is possible to suppress the welded portion from excessively protruding from the top end of base. Further, when welding the conductors, it is also possible to form the insulating portion that is insulating the top end of base and the threaded base at a position away from the welded portion. Accordingly, heat generated when welding is hardly transmitted to the insulating portion and it is possible to prevent cracks from producing on the insulating portion and the top end of base from coming off the insulating portion.
Further, according to the present invention, there is provided a lamp apparatus manufacturing method comprising the steps of electrically connecting a first conductor to a top end of base at one side of a base and a second conductor to a threaded portion at the other side, wherein the top end of base has a flat portion and a cylinder portion that has a through hole penetrating the flat portion at nearly the center of the flat portion and a cylinder portion is formed protruding from the flat portion; mounting the base to a lamp body; and welding the cylinder portion and the first conductor by mutually fusing in the state with the top end of the first conductor inserted into the through hole.
According to the lamp apparatus manufacturing method of the present invention, when the inner diameter of the through hole is made larger than the outer diameter of the conductor, it becomes extremely easy to insert the conductor into the through hole. Even in this case, the cylinder portion and the conductor can be certainly connected electrically when the cylinder portion is crushed. Accordingly, when welding the cylinder portion and the conductor, both of them can be fused.